Interpretive Summary: Using animal manure as fertilizer in row crop production has been encouraged. Substantial studies have been conducted to determine the effects of broiler litter on corn and cotton. Application of broiler litter to row crops occurs either in the fall or in the spring. Timing of manure applications has a critical effect on available plant nutrients and provides the best agronomic response in most instances. The incorporation of broiler litter for cotton production at different times of the year should significantly influence N availability, cotton growth and yield. Fertilizer effectiveness of broiler litter N has shown to increase with spring application compared to fall application due to reduction in N leaching losses. In Mississippi, due to wet winter months and high precipitation in early spring, broiler litter is applied in the fall to prevent delayed planting in the spring. However, fall application of broiler litter over a winter fallow, resulted in considerable N leaching loss. Any cultural practices that prevent or reduce N loss from leaching during the winter and recycle the mineralized N for the subsequent crops in the spring could be beneficial to the producers. Cover crops have been promoted as a means of maximizing the efficient use of available N to subsequent crops in agricultural systems resulting in reduced risk of environmental problems associated with NO3 contamination of surface and ground water while potentially enhancing profitability through a reduced fertilizer N requirement. Results from the first year of this study indicated that over seeding a catch crop to fall applied broiler litter for cotton production appeared to be a desirable cultural practice from N standpoint, maximizing the efficient use of available N from broiler litter applications for subsequent cotton growth and yield and resulting in reduced risk of environmental problems.

Technical Abstract:
This experiment was conducted on a Leeper silty clay loam soil at Mississippi Agricultural and Forestry Experimental Station (MAFES), Mississippi State, MS, in 2003 and will continue to 2006 to identify if rye winter cover crop over seeded to fall applied broiler litter benefits cotton growth and yield. The Experimental design was a randomized complete block with a split-plot arrangement of treatments. The main plots are rye (Secale cereale L.) winter cover crop and winter fallow and the sub-plots are broiler litter application rates of 0, 4.5, 9, and 13.4 mg ha-1. Averaged across broiler litter application rates, cotton plant height and number of bolls at maturity were 18 and 24% greater with rye-cotton cropping system than those with winter fallow. At high broiler litter application rate, cotton lint yield and N content were 10 and 33% greater in rye winter cover crop than those in winter fallow plots, indicating greater N availability from the soil residual N and the potential of N mineralization from decomposition of cover crop residue. In the spring after killing cover crop and before planting cotton, soil residual NO3-N concentrations in rye winter cover crop at 30 cm depth (19-23 mg kg-1) were 50-62% lower than in winter fallow (38-60 mg kg-1), respectively, indicating the ability of rye cover crop in sequestering soil NO3-N. In the fall after harvesting cotton, soil NO3 concentrations in the rye-cotton cropping system at the high broiler litter application rate in the 0-60 cm depth (13 mg kg-1) was 50% lower than that of in the winter fallow-cotton (26 mg ha-1), reflecting the greater potential of N leaching loss for winter fallow. Over seeding a catch crop to fall applied broiler litter for cotton production appears to be agronomically and environmentally beneficial.